AT&T confirmed attackers have compromised the security of a number of its Mobility wireless unit members. Outside attackers, allegedly employees of one of AT&T's service providers, stole personal information including Social Security numbers and call records.

AT&T believes that the attackers were seeking to sell stolen AT&T phones on second-hand markets.

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Affected AT&T customers should have received a notification from the carrier. "If those who stole the codes were merely interested in unlocking the stolen phones, then only the stolen phones are at risk," said Mike Prospero, reviews editor at Tom's Guide. "However, since social security numbers were stolen as well, those affected should take steps to monitor their credit scores," Prospero added.